Muscle mass decreases with age

Aging brings many changes and challenges, and ranking near the top is the condition known as sarcopenia. It’s a fancy word meaning the degenerative loss of muscle mass, and along with it comes a big hit to the quality of life. Less muscle mass means less strength, which, in turn, makes the demands of everyday living more difficult.

Sarcopenia is not a disease and can occur in healthy people. It occurs primarily because of hypokinesia, another fancy word that means reduced body movement, or sedentary living. The accumulating effects of hypokinesia over many years contribute to progressive sarcopenia. The effects come on gradually, and as with cancer and heart disease, folks typically don’t know it’s happening until it’s quite advanced, and they begin struggling to do things that used to come easily, like climbing stairs, or lifting and carrying weighty objects. When sarcopenia is advanced, it’s a major threat to independent living.

Fortunately, today, folks are more aware that sarcopenia lurks nearby with its devastating consequences, and for that reason, I am frequently asked for advice on how to hold on to muscle mass as the years roll on. Here, in the next series of columns, is what you need to know, and the earlier in life you know it, the better.

Beware the downhill slide

How much of the loss of muscle mass is caused by aging, and how much by hypokinesia? For most Americans, the lion’s share of lost muscle mass with age is caused by hypokinesia (physical inactivity). Starting around age 30, the body’s muscle mass peaks, then from there things are likely to go downhill. But the slope of the downhill slide is largely up to you. If you are physically inactive, the slope is steep. You can lose as much as 1 percent of your muscle mass per year after age 30 if you do nothing to slow the trend. This means by age 80, your muscle mass can be reduced by half.

With advanced age, say 70 and above, the impact of hypokinesia accelerates. In other words, the older you get, the greater the devastation caused by being physically inactive.

This means regardless of age, there’s a lot you can do to help yourself. Indeed, physically active folks do a better job of holding on to muscle, and it’s certainly possible to be reasonably strong and capable throughout the life span.

Realistic expectations

OK, so you are now persuaded to do all you can to stop the downhill slide. What is possible to accomplish with dedicated effort? Quite a bit, and I’ll discuss this next week, but you have to be realistic and not set your sights too high, because some loss of muscle mass is inevitable. In other words, at age 60 you won’t be as good as you were at 30, no matter what you do, or how hard, or how often you work out. The reason is, eventually, the body’s physiology begins to work against you. Here’s how:

First, with age there is a decrease in the body’s ability to synthesize proteins (create proteins from amino acids, the basic components). Muscle is mostly protein and water, and as is true of all cells in the body, muscle cells are constantly dying and needing to be replaced. This is a relentless process, and the body must always be manufacturing new cells. However, since with age it takes longer to synthesize muscle proteins, we fall behind in the replacement process, and the older we get, the worse it gets.

Other physiological changes occur with aging, as well. There is a decline in nerve cells, which means it’s harder for the brain to stimulate muscle contractions through the nerves. Hormone production that supports muscle mass wanes as well, including growth hormone and testosterone.

The bottom line is, aging takes a toll on the muscles, but there is much you can do to determine how great that toll is going to be. More on this next week.

Bryant Stamford is professor and chairman of the department of kinesiology and integrative physiology at Hanover College. To contact him, email stamford@hanover.edu.